Examples of currently-used apparatus of the above type include a recording device that records an image to a recording medium to be transported. The recording device includes a plurality of inkjet recording heads, a scanner, and a controller (disclosed, for example, in Japanese Patent Publication No. 2013-252641A).
The recording heads print an inspection pattern onto the recording medium. The scanner scans the inspection pattern. The controller calculates shift amounts of recording positions printed onto the recording medium by the recording heads in accordance with information scanned by the scanner, and provides adjustment data based on the shift amounts to the recording heads individually. The recording heads each change its printing timing with the adjustment data, whereby the recording positions of the recording heads are shifted in a transportation direction of the recording medium.
However, the example of the currently-used device with such a configuration possesses the following drawbacks. That is, the currently-used device has difficulty in efficiently monitoring a temporal variation in shift amount of the recording positions caused by operation of a printing apparatus. Monitoring the variation in shift amount requires constant and continuous printing of the inspection pattern by the recording heads as well as constant and continuous scanning of the inspection pattern by the scanner. Moreover, the currently-used device has difficulty in obtaining a real-time variation in shift amount correctly. A time lag occurs between generation of a shift and detection of the shift, the time lag having a longer time period than that during movement of the recording medium from below the recording heads to below the scanner. As a result, the currently-used device cannot adjust the printing timings of the recording heads correctly.